In residential construction, there is often the need to provide an exhaust vent from a room, particularly a kitchen or a bathroom, directly to the outside. Such exhaust vents typically comprise vertical pipes or conduits which have at their lower end a fan. Upon activation the fan causes air to be exhausted from the room through the conduit to the outside.
In the past, it has been common to provide a vent cover which includes a one-way valve at the exit end of the conduit. Upon the vent being activated, the pressure increases in the conduit and the one-way valve opens to allow the air to exit from the conduit. Typically, such vent covers are formed from metal and the opening and closing of the vent cover is associated with a tinny clanking noise. Under the influence of wind or the like, the valve may be caused to open causing a clanking noise which is carried down the pipe, and through the vent into the living space. For bathrooms associated with bedrooms, this clanking noise can be a source of irritation to anyone trying to sleep. In extreme climates, unwanted opening of the valve can also allow cold or hot air to enter the conduit and can affect the comfortable temperature inside the building. Additionally, the prior designs are susceptible to rain or the like leaking in through the exhaust cover and down the conduit.